1. Field of the Invention
The present invention relates generally to corneal contact lens and their use in treating myopia. More particularly, the present invention involves a corneal contact lens which is shaped to provide altering of the patient's cornea during continued wear in a manner which reduces the myopic condition.
2. Description of Related Art
Myopia, also known as nearsightedness, is a condition where the radius of curvature of the cornea is smaller than normal. Individuals with this condition have difficulty in focusing on distant objects because the cornea is curved too sharply to provide adequate focusing. Myopia is a common condition for which no entirely suitable permanent treatment has been developed.
One approach to correcting myopia is through surgical reshaping of the cornea. However, such surgical procedures have not been entirely proven and there is some question as to the permanency of the surgically altered lens shape. Another approach is to alter the corneal shape by wearing corneal contact lenses which are designed to continually bias or exert pressure on the cornea to gradually force or mold the cornea into the desired normal corneal curvature. A retainer lens is then worn on a part-time basis to prevent the cornea from returning to its original shape. This method of treatment is commonly referred to as orthokeratology.
The success of any treatment by orthokeratology is dependent upon the shape and structure of the corneal contact lens. There presently is a need to provide lens shapes which are useful in promoting relatively rapid and safe reshaping of the myopic cornea. Further, such corneal contact lenses must be comfortable to wear and provide acceptable vision correction during the cornea reshaping process.